Download - A Type Driven Approach to Functional Design
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A Type Driven Approach to Functional Design
Michael FeathersGroupon
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A Type Driven Approach to Functional Design
Michael FeathersGroupon
(just because)
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a
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[a]
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map :: (a -> b) -> [a] -> [b]
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map :: (a -> b) -> [a] -> [b]
map (+2) [1,2,3]
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region 7 9 “expertsexchange”
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region 7 9 “expertsexchange”
region :: Int -> Int -> String -> String
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regionFrom7 9 “expertsexchange”
regionFrom7 :: Int -> Int -> String -> String
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Hoping
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Line Break algorithm
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String -> String
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String -> [String] -> [[String]] -> [String] -> String
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String -> [String] -> [[String]] -> [String] -> String
breakTextIntoWords
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String -> [String] -> [[String]] -> [String] -> String
breakTextIntoWords
breakWordsIntoLines
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String -> [String] -> [[String]] -> [String] -> String
breakTextIntoWords
breakWordsIntoLines
joinWordsInBrokenLines
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String -> [String] -> [[String]] -> [String] -> String
breakTextIntoWords
breakWordsIntoLines
joinWordsInBrokenLines
joinBrokenLines
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String -> [String] -> [[String]] -> [String] -> String
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String -> [String] -> [[String]] -> [String] -> String
String -> [String] -> (Int -> [[String]]) -> [[String]] -> [String] -> String
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String -> [String] -> [[String]] -> [String] -> String
String -> [String] -> (Int -> [[String]]) -> [[String]] -> [String] -> String
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String -> [String] -> [[String]] -> [String] -> String
String -> [String] -> (Int -> [[String]]) -> [[String]] -> [String] -> String
Abuse!
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A Design Device
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(via Scott Ambler)
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(via Scott Ambler)
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String -> [String] -> [[String]] -> [String] -> String
words
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String -> [String] -> [[String]] -> [String] -> String
words
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String -> [String] -> [[String]] -> [String] -> String
wordsbrokenLines
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String -> [String] -> [[String]] -> [String] -> String
wordsbrokenLines
wordJoinedLines
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String -> [String] -> [[String]] -> [String] -> String
wordsbrokenLines
wordJoinedLines
joinedLines
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Favors combinator style
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Favors combinator style
[String] -> Int
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Favors combinator style
[String] -> Int
[String] -> [Int] -> [Int] -> [Int] -> Int
(repeated types in endomorphic chain)
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Affordances
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Separate bins for your head and your notation
String -> [String] -> (Int -> [[String]]) -> [[String]] -> [String] -> String
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Concentrates on Data
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Concentrates on Data
..in naming
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Favors combinator style
Staying in the same shape is the easiest way to get from here to there
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Thank you